That is for example what our language is. Instead of presenting people with the actual thing or situation we are talking about, we just exchange words. The words and sentences are symbols that refer to real or imagined events and views or ideas about them, or about other ideas and views. Language can be very, very useful.
It is, however, very important for one's sanity to be aware of the degree to which we are abstracting. If we lose track of it and start using the abstractions as if they were real, that leads to aberration. Consciousness of abstracting is a valuable ability to have. Then one can simplify things as necessary for the purpose of communication, but one can also see things the way they really are when that is appropriate.
This is a scale of degrees of abstraction:
The universe is what it is. If we grasp the totality of even the most minute sub-atomic processes going on in front of us, then we could say with some approximation that we connect with what is going on. But it could also be simplified into the major process that is going on, i.e. a car is driving by. That is vastly over-simplified compared with looking at the movement of every single electron and so forth. But for human use that is perfectly allowable. Now somebody comes along and perceives the car driving by. She might see colors and shapes, she might hear sounds, and so forth. That is not the complete story, it is just a certain snapshot, limited by the distortions and range of human perceptions. Now the person might attach names or labels to what is going on. "A Car" she might say. That is an abstraction, a simplification of what she actually perceives. She might use some abstract numbers or terms to describe if further. It is a "1976 Ford Taurus with a California license plate". That refers to a whole bunch of things that are greatly over-simplified. Then we can make inferences based on what we have arrived at so far. We can infer that the car is going somewhere, that it is driven by somebody with a driver's license, that it has a steering wheel and a brake pedal, even though we can't see them. We can get more abstract and infer that the driver is probably drunk or went to a driving school of low quality, which gets us into opinions and assumptions. We can make an judgment about it. "He is an idiot". We can generalize the whole thing into an idea like "Old people can't drive cars" or something.
Each step takes us further and further away from what is actually taking place. We are adding abstractions of abstractions to each other. We are using symbols about symbols about symbols and so forth.
That is all fine, as long as it serves a purpose and as long as we don't lose track of where we started.
If a person loses track of how much she has abstracted and over-simplified things, then it is time to reverse that process. Particularly we would like people to get in close contact with what can actually be perceived as going on. In the human realm we can't get much further. However, the person should be aware of that also perceptions are abstractions. Just because she perceives it, doesn't mean that others will agree. Different people will extract different perceptions out of a situation. But if she is at least in touch with her own perceptions, she will be in a better shape than if she is only operating on ideas about ideas about something she heard once.
Semantic Processing is about developing consciousness of what levels of abstraction one is using and about getting closer to the process level of reality. That is, becoming aware of how reality consists of processes one can perceive.